Issue 2399 part 1: In debugger allow modifying local variable values

src/debug-debugger.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1409 matching lines @@
       } else if (request.command == 'listbreakpoints') {
         this.listBreakpointsRequest_(request, response);
       } else if (request.command == 'backtrace') {
         this.backtraceRequest_(request, response);
       } else if (request.command == 'frame') {
         this.frameRequest_(request, response);
       } else if (request.command == 'scopes') {
         this.scopesRequest_(request, response);
       } else if (request.command == 'scope') {
         this.scopeRequest_(request, response);
+      } else if (request.command == 'setVariableValue') {
+        this.setVariableValueRequest_(request, response);
       } else if (request.command == 'evaluate') {
         this.evaluateRequest_(request, response);
       } else if (lol_is_enabled && request.command == 'getobj') {
         this.getobjRequest_(request, response);
       } else if (request.command == 'lookup') {
         this.lookupRequest_(request, response);
       } else if (request.command == 'references') {
         this.referencesRequest_(request, response);
       } else if (request.command == 'source') {
         this.sourceRequest_(request, response);
@@ skipping 506 matching lines @@
     if (index < 0 || this.exec_state_.frameCount() <= index) {
       return response.failed('Invalid frame number');
     }
 
     this.exec_state_.setSelectedFrame(request.arguments.number);
   }
   response.body = this.exec_state_.frame();
 };
 
 
-DebugCommandProcessor.prototype.frameForScopeRequest_ = function(request) {
+DebugCommandProcessor.prototype.resolveFrameFromScopeDescription_ =
+    function(scope_description) {
   // Get the frame for which the scope or scopes are requested.
   // With no frameNumber argument use the currently selected frame.
-  if (request.arguments && !IS_UNDEFINED(request.arguments.frameNumber)) {
-    frame_index = request.arguments.frameNumber;
+  if (scope_description && !IS_UNDEFINED(scope_description.frameNumber)) {
+    frame_index = scope_description.frameNumber;
     if (frame_index < 0 || this.exec_state_.frameCount() <= frame_index) {
       throw new Error('Invalid frame number');
     }
     return this.exec_state_.frame(frame_index);
   } else {
     return this.exec_state_.frame();
   }
 };
 
 
 // Gets scope host object from request. It is either a function
 // ('functionHandle' argument must be specified) or a stack frame
 // ('frameNumber' may be specified and the current frame is taken by default).
-DebugCommandProcessor.prototype.scopeHolderForScopeRequest_ =
-    function(request) {
-  if (request.arguments && "functionHandle" in request.arguments) {
-    if (!IS_NUMBER(request.arguments.functionHandle)) {
+DebugCommandProcessor.prototype.resolveScopeHolder_ =
+    function(scope_description) {
+  if (scope_description && "functionHandle" in scope_description) {
+    if (!IS_NUMBER(scope_description.functionHandle)) {
       throw new Error('Function handle must be a number');
     }
-    var function_mirror = LookupMirror(request.arguments.functionHandle);
+    var function_mirror = LookupMirror(scope_description.functionHandle);
     if (!function_mirror) {
       throw new Error('Failed to find function object by handle');
     }
     if (!function_mirror.isFunction()) {
       throw new Error('Value of non-function type is found by handle');
     }
     return function_mirror;
   } else {
     // No frames no scopes.
     if (this.exec_state_.frameCount() == 0) {
       throw new Error('No scopes');
     }
 
     // Get the frame for which the scopes are requested.
-    var frame = this.frameForScopeRequest_(request);
+    var frame = this.resolveFrameFromScopeDescription_(scope_description);
     return frame;
   }
 }
 
 
 DebugCommandProcessor.prototype.scopesRequest_ = function(request, response) {
-  var scope_holder = this.scopeHolderForScopeRequest_(request);
+  var scope_holder = this.resolveScopeHolder_(request.arguments);
 
   // Fill all scopes for this frame or function.
   var total_scopes = scope_holder.scopeCount();
   var scopes = [];
   for (var i = 0; i < total_scopes; i++) {
     scopes.push(scope_holder.scope(i));
   }
   response.body = {
     fromScope: 0,
     toScope: total_scopes,
     totalScopes: total_scopes,
     scopes: scopes
   };
 };
 
 
 DebugCommandProcessor.prototype.scopeRequest_ = function(request, response) {
   // Get the frame or function for which the scope is requested.
-  var scope_holder = this.scopeHolderForScopeRequest_(request);
+  var scope_holder = this.resolveScopeHolder_(request.arguments);
 
   // With no scope argument just return top scope.
   var scope_index = 0;
   if (request.arguments && !IS_UNDEFINED(request.arguments.number)) {
     scope_index = %ToNumber(request.arguments.number);
     if (scope_index < 0 || scope_holder.scopeCount() <= scope_index) {
       return response.failed('Invalid scope number');
     }
   }
 
   response.body = scope_holder.scope(scope_index);
 };
 
 
+// Reads value from protocol description. Description may be in form of type
+// (for singletons), raw value (primitive types supported in JSON),
+// string value description plus type (for primitive values) or handle id.
+// Returns raw value or throws exception.
+DebugCommandProcessor.resolveValue_ = function(value_description) {
+  if ("handle" in value_description) {
+    var value_mirror = LookupMirror(value_description.handle);
+    if (!value_mirror) {
+      throw new Error("Failed to resolve value by handle, ' #" +
+          mapping.handle + "# not found");
+    }
+    return value_mirror.value();
+  } else if ("stringDescription" in value_description) {
+    if (value_description.type == BOOLEAN_TYPE) {
+      return Boolean(value_description.stringDescription);
+    } else if (value_description.type == NUMBER_TYPE) {
+      return Number(value_description.stringDescription);
+    } if (value_description.type == STRING_TYPE) {
+      return String(value_description.stringDescription);
+    } else {
+      throw new Error("Unknown type");
+    }
+  } else if ("value" in value_description) {
+    return value_description.value;
+  } else if (value_description.type == UNDEFINED_TYPE) {
+    return void 0;
+  } else if (value_description.type == NULL_TYPE) {
+    return null;
+  } else {
+    throw new Error("Failed to parse value description");
+  }
+};
+
+
+DebugCommandProcessor.prototype.setVariableValueRequest_ =
+    function(request, response) {
+  if (!request.arguments) {
+    response.failed('Missing arguments');
+    return;
+  }
+
+  if (IS_UNDEFINED(request.arguments.name)) {
+    response.failed('Missing variable name');
+  }
+  var variable_name = request.arguments.name;
+
+  var scope_description = request.arguments.scope;
+
+  // Get the frame or function for which the scope is requested.
+  var scope_holder = this.resolveScopeHolder_(scope_description);

[Yang, 2012/11/27 16:46:23]

Somewhat confused. In here you pass request.arguments.scope to
resolveScopeHolder_ but in some places you pass request.arguments to
resolveScopeHolder_.

[Peter Rybin, 2012/11/27 18:24:28]

I checked it again. It should be OK. For the new commands I'm trying to put
scope holder reference in a separate object (to better structure it and to make
scopes replacable). Old commands (such as 'scopes' and 'scope') have the same
properties on the arguments level. I should support both cases.

Do you think some comment is required about this?

+
+  if (IS_UNDEFINED(scope_description.number)) {
+    response.failed('Missing scope number');
+  }
+  var scope_index = %ToNumber(scope_description.number);
+
+  var scope = scope_holder.scope(scope_index);
+
+  var new_value =
+      DebugCommandProcessor.resolveValue_(request.arguments.newValue);
+
+  scope.setVariableValue(variable_name, new_value);
+
+  var new_value_mirror = MakeMirror(new_value);
+
+  response.body = {
+    newValue: new_value_mirror
+  };
+};
+
+
 DebugCommandProcessor.prototype.evaluateRequest_ = function(request, response) {
   if (!request.arguments) {
     return response.failed('Missing arguments');
   }
 
   // Pull out arguments.
   var expression = request.arguments.expression;
   var frame = request.arguments.frame;
   var global = request.arguments.global;
   var disable_break = request.arguments.disable_break;
@@ skipping 610 matching lines @@
     case 'string':
     case 'number':
       json = value;
       break;
 
     default:
       json = null;
   }
   return json;
 }
+
+Debug.TestApi = {
+  CommandProcessorResolveValue: DebugCommandProcessor.resolveValue_
+};